Sulphur is a pale yellow, brittle solid. Sulphur is an idiochromatic mineral, so-called because they are nearly always the same colour as certain light absorbing atoms are an essential element of the mineral's atomic structure. It exists as a crystalline solid of S8 molecules. The eight sulphur atoms are arranged in a ring so as to form a crown shape. These molecules can stack together in two different ways, so there are two different crystalline forms of sulphur called rhombic and monoclinic, following the arrangements of the atoms within the crystals. Rhombic sulphur is the more stable form. There is also a third allotropic form of sulphur: an amorphous form.
The power needed to lift a firework into the night sky is provided by a slow-burning combination of 75% potassium nitrate, 15% charcoal, and 10% sulphur.